Mobile phone dominates the phone market today and its number will soon surpass that of the conventional wired telephone. Meanwhile, mobile phone equipped with camera has become a trend as well. Thus, only a mobile phone system with reliable electrical properties and fashionable appearance will lead in today's market.
A mobile phone system with a camera is usually called a multimedia mobile phone system. The multimedia mobile phone system normally has an RF (Radio Frequency) module, a baseband module, a camera, and one or two display screens. The baseband module receives radio frequency signals from the RF module; or it transmits radio frequency signals to other mobile phone systems or mobile phone stations with the assistance of the RF module. The RF module has an antenna to convert the radio frequency signals into an electromagnetic wave. Conversely, it can receive an electromagnetic wave and then convert the electromagnetic wave into a radio frequency signal for further processing by the baseband module.
In the baseband module, the radio frequency signal with high frequency carrier is sampled out from the carrier. That is, the higher frequency portion of the original radio frequency signal is filtered out. Thus, the filtered radio frequency signal falls in the range of baseband frequency. The baseband module is an interface between wireless antenna and the digital portion of the mobile phone system, which processes calling information including video or audio signals or voice signals for users. Moreover, the baseband module can transmit text messages to others through the RF module.
The baseband module may also control a display screen. The baseband module can send display information to the display screen and then show the information on the screen, creating a friendly interface between users and the machinery of the phone system. However, for a mobile phone with multimedia functions, e.g., cameras or display panels, it usually requires a multimedia module or processor. For example, the multimedia module can process images captured by a digital camera. This digital image processing includes white balance, automatic exposure, or pattern classification based on the captured scenes. In another example, the multimedia module can process video signals from the baseband module, e.g., video information sent by a friend or a movie sent by a service provider. The video may contain compressed video information including AVI (Audio Video Interleave), MPEG 2 (Moving Picture Experts Group 2), or MPEG 4 compression format, and need to be decompressed on the receiver's end. Besides the video compression standards mentioned here, there are also many compression standards relate to voice signals.
Today, the wireless mobile phones can further receive TV programs or GPS (Global Positioning System) directions from satellites. Obviously, the modern wireless mobile phone is no longer a simple device for voice application only. In order to integrate desirable multimedia functions into a compact, mobile device, a scheme should be provided such that the complex multimedia mobile phone system can handle all data correctly and in real time.
Taiwan Pat. No. 1229,552 to Zhang, entitled “Method and apparatus with applications for image data transmission,” discloses an apparatus that bypasses image data from an image processor to a display device without being handled by a CPU (Central Processing Unit) to buffer the image data and send the image data to the display device. The disclosure of which is hereby incorporated by reference. The function of the apparatus is similar to a DMA (Direct Memory Access) controller in a computer where the DMA controller bypasses the content of the memory to several peripheral connected devices. The resources of the CPU are therefore saved and can be used for other functions. However, the transmission method described by this patent requires complex parallel data buses, and therefore, the interconnection between each components becomes complicated.
Taiwan Pat. No. 1241,821 to Zhang, entitled “Mobile phone architecture and method thereof for performing voice service and capturing or watching images simultaneously,” discloses a mobile phone architecture with a switch control unit that can isolate a parallel communication between a digital baseband unit and a display module to send image data from an image processing module to the display module. The disclosure of which is hereby incorporated by reference. However, this patent only utilizes parallel scheme to transmit data between the digital baseband module and the display module. Moreover, the disclosure does not mention how to use a multimedia processor to construct a simplified mobile phone system with low cost communication scheme.